1. Field of the Invention
The present invention relates to a material transfer assembly used in conjunction with a conveyor system and an unloading apparatus to transfer bulk materials from relatively large cargo containers or vessels to a material transport, handling or storage system. More particularly, this invention relates to a transfer assembly used in conjunction with an unloading apparatus and a conveyor system to transfer dry cement or other powdered material from the unloading apparatus to a material transport, handling or storage system.
The transfer of various bulk materials presents difficult problems; however, bulk cement, because of its physical properties, is particularly troublesome. Dry cement is a fine powdered material, 100 mesh or under in size. It is mildly abrasive, and it flows relatively freely at an angle of repose of 30.degree. to 45.degree.. When aerated it becomes fluid-like, but when packed or settled, it becomes dense and difficult to handle. It has strong adhesive properties when combined with water, and it deteriorates drastically when exposed to moisture. Once properly mixed, it sets and hardens very quickly.
When the cement is in its fluffy, aerated condition, it poses unique handling and transport problems. If the container used to hold the cement or the system used to transport it are open to the elements, the wind blows away the dust-like particles of cement. In addition to the loss of the product, cement particles in the air present a number of problems. They create a harsh environment which accelerates the wear of equipment and creates a health hazard to people who must work in this environment.
If the containers or transport system are open to moisture, the cement will combine with the water, set and quickly harden into a solid mass. When it combines with water, but before it hardens, cement has strong adhesive properties, and in this state it may adhere to the equipment, resulting in wear or failure of the equipment and in undesirable and expensive downtime. Cement which has combined with water and set is waste material requiring disposal. The cost of lost material and disposal is also an undesirable expense.
2. Description of the Prior Art
In view of the material handling parameters outlined above, a material transfer assembly for a mobile unloading apparatus which transfers bulk material from a vessel into a conveyor disposed within a fixed and closed housing should include the following features. The transfer assembly must provide a closed conduit which will transfer bulk material from the unloading apparatus to the conveyor without exposing it to the elements or allowing it to come into contact with other equipment. The assembly should move along with the unloading apparatus to reduce the extent of movement and the duration of operation of the unloading apparatus, thus reducing wear of the equipment, fuel consumption and ultimately, the expense of operation. In addition, the transfer assembly should be flexible so that the unloading apparatus may operate smoothly, without interruption and without damaging any related components. Added flexibility would reduce the need for strict requirements and precise tolerances, minimizing the expense of manufacture and assembly. It would allow the transfer assembly to accommodate variations in the relative positioning of the mobile unloading apparatus and the fixed conveyor. Accurate positioning of the unloading apparatus relative to the conveyor greatly increases the expense of manufacture and assembly.
The transfer assembly of the present invention, used in conjunction with a mobile unloading apparatus and a conveyor with a flexible cover, fulfills these requirements. It is simple, flexible, durable, and mobile. It allows the unloading apparatus to locally displace the flexible conveyor cover at the point of deposit and to deposit cement anywhere along the length of the conveyor regardless of variations in alignment between the receiving conveyor and the carriage path.